Quality Indices for Aluminum Alloy Castings: A Critical Review

Abstract

Several indices are available in the literature to assess the structural quality of cast Al alloys, especially Al-7 pct Si-Mg alloys that are based on tensile test results. Some of these indices, most notably the one developed by Drouzy et al., provide a number that necessarily does not have a physical meaning, whereas the others are a measure of what fraction of the expected tensile performance is achieved. These indices are analyzed in depth, their similarities and shortcomings are discussed in detail, and recommendations are made.

Microstructure and mechanical properties of Al–Si cast alloy with additions of Zr–V–Ti

“…Therefore, the tensile strength and ductility of the material are essential parameters for the material quality characterization. From the tensile test data, the quality index, Q index , was calculated using following expression [32,8]:…”

Fatigue life of ablation-cast 6061-T6 components

“…This is consistent with the elongation values for the two materials: 15.7% for ablation-cast 6061 and only 5% for conventionally sand cast A356. Because elongation is a measure of how much energy a specimen will absorb before fracture [21] it is a good indication of the structural quality of the metal [22] with higher structural quality metal yielding higher elongation. Note that an elongation of 21.8% can be obtained in A356-T6 alloys for s y ¼230 MPa [23], and therefore the 5% elongation of A356-T6 castings reported by Raju et al [17] represents only 23% of the potential elongation that can be obtained with higher quality melt and better filling systems.…”

On the ductility potential and assessment of structural quality in Mg alloy castings

“…That is why efforts to increase ductility by changing heat treatment, a practice promoted in traditional metallurgy books as strength-ductility trade-off, has often been fruitless [14,17]. A more effective strategy to increase ductility is to improve the initial melt quality, eliminate liquid metal transfers and design the filling system carefully so that additional oxide bifilms are not entrained [14,19,20].…”